Recently, as a method of obtaining a semiconductor module having a three-dimensional multilayered structure, a technique has been studied which joins individual semiconductor chips divided from each other to laminate the semiconductor chips. However, in order to reduce a cost for lamination, another method is also being studied in which a plurality of semiconductor wafers are joined first before being divided into semiconductor chips, and then the structure resulting from the joining is divided into individual semiconductor chips.
Moreover, examples of the method of joining semiconductor wafers include a direct bonding method which uses a technique of hydroxyl bond or plasma activation and is carried out at the room temperature, a resin bonding method which uses a resin material, and the like.